ENERGY: UCSD profs win $1.5M to study solar integration with grid

For a day at the beach, occasional cloud cover can be annoying; for a power company getting a lot of electricity from solar power, occasional cloud cover can be cause for alarm.

Profs.
Jan Kleissl
and
Carlos Coimbra
, both engineering professors at UC- San Diego, will tackle the problem for the next two years thanks to a $1.5 million grant from the California Public Utilities Commission approved Thursday. Specifically, the pair will try to predict the presence of marine layer clouds up to 24 hours in advance, and they'll create short-term predictions of cloud cover that will help utilities manage rapid drops in production from customers with solar panels on their houses.

"The key word is integration," Kleissl said. "In previous rounds (of funding) they have funded development of forecasting for variability of solar power. Now we're taking those models and proving them a little more and making sure they get implemented in a utility environment."

In its effort to combat greenhouse gas emissions, California has been ramping up electricity generation from renewable sources like solar and wind. San Diego Gas & Electric Co. and Southern California Edison met a goal to purchase 20 percent of their power from renewable sources in 2011, and both San Diego and Riverside counties set records for the most residential solar installations last year, according to the California Solar Initiative.

But solar power generators pose challenges for utilities because they produce less power on cloudy days, and their production can change suddenly when clouds pass overhead.

Kleissl has been studying the effects of weather changes on solar power. Last year, he
developed a model
to predict the effects of changing weather on solar production.

He plans to build on that work with the grant money. SDG&E will let him study three to five residential neighborhoods with unusually high concentrations of solar installations.

Kleissl, Coimbra and their students install sensors around those neighborhoods to predict cloud cover with 5 to 30 minutes of lead time. That should be enough time for SDG&E to bring in power from another source when the solar panels stop producing.

The team will also study historical weather data to predict which days will suffer from a thick marine layer.

Kleissl also said the work will help the local economy.

"I'll have eight students on this project," he said. "I'll be creating a very educated workforce, and making the county a better place for solar."